JPS58151939A - Continuous casting device - Google Patents

Abstract

PURPOSE:To provide a continuous casting device which prevents the erosion of a casting mold, enables long-term casting, prevents sticking of an ingot and makes drawing easy, by constituting the mold and a conduit of cermet having heat resistance, lubricity and corrosion resistance. CONSTITUTION:In a horizontal and continuous casting device, the molten metal 14 in a ladle 1 flows through an immersion nozzle 3 into a tundish 5 at the flow rate requlated with a sliding nozzle 2, passes through a refractory conduit 7 provided in the bottom part thereof and flows into a nozzle mold pipe 8 made of cermet such as molybdenum-zirconia. The mold part is cooled with a water-cooled jacket 9 from the outside. The solidification initiates from the inside of the nozzle on the slightly upper stream side than the cooled part, and a solidified shell 15 is drawn on roll groups 10 by means of pinch rolls 12 under cooling by water spray groups 11. The ingot obtd. by the above-mentioned horizontal and intermittent drawing has just slight drawing marks and does not require leveling.

Description

[Detailed description of the invention] The present invention relates to a continuous casting apparatus for molten metal.

#ll Continuous casting (hereinafter abbreviated as CC) of gold metal and steel is generally performed by I! lid casting.If the overall length of the equipment is straightened, the equipment becomes too high, so casting A method of pulling out the slab along a curved path is often used, but in curved CC, the height of the equipment is quite high), and the static pressure of unsolidified molten steel inside the slab is used to pull out the slab. It has disadvantages such as aggravation of center segregation, formation of single-piece defects due to horizontal correction of curved slabs, and complication of equipment due to sacrificial treatment.

On the other hand, in horizontal CC, where the mold is arranged horizontally and the slab is pulled out directly in the horizontal direction, the equipment height is low, the equipment configuration is simple, the static pressure of molten steel is kept low, and the casting It has the advantage of not requiring single-sided correction.

Therefore, various methods of horizontal CC have been attempted, but
Hagane no Mizuko cc#i It has not yet become popular, except for a few.

The problems that are preventing the generalization of horizontal CC for steel are that static pressure of molten steel is applied to the solidified shell and lubricant cannot be supplied to the gap between the shell and the mold. 2) To prevent sagging during ζO sticking, pull out intermittently (see Figure 1) to prevent stickiness during downtime. Buri and gin the shell and the drawn shell! Repair and pull out (and #! Fixed tip nozzle (sometimes called f rake ring) -
A serious defect called cold shut occurs at the part of the slab where the temperature difference between the two temperatures overlaps.

Figure 2 is a diagram schematically showing the solidification state during the intermittent drawing process ■ to ■ in Figure 1. Figure 2 (a) is a hot tear diagram of surface defects in the horizontal CC plate ring-copper mold method. The generation process of cold shut (0) is shown along with the progress of solidification. Figure (b) shows the graphite mold method. In the figure, B is the plate ring, and W is the cooling water. , t indicates the center of the mold, ■ indicates a copper plate, ■ indicates a copper bowl, and t indicates graphite.

One way to solve the above-mentioned problems is to reduce the cold shut by shortening the withdrawal-stop cycle time of intermittent withdrawal.
Cold shut cannot be solved as long as there is a step at the mold boundary, and new problems arise such as the complexity of the equipment due to the shortening of the cycle time and the inability to increase the size of the slab.

On the other hand, for cast iron, the nozzle-mold is formed from a single graphite tube, the outer periphery of the graphite in the mold is cooled with a water-cooling jacket, and horizontal casting is performed by intermittent drawing. In this case, since there is no step at the nozzle-mold boundary, no cold shut is generated, and only hot tears are generated as slight pull-out marks (see FIG. 2B). However, graphite has a solubility in most #1 metals, and is particularly unusable in molten steel because it is dissolved and eroded by high temperatures.

The present invention was achieved as a result of careful study and testing of these conventional techniques. In other words, one way to put horizontal CC into practical use is to develop conduit nozzle-mold materials that have heat resistance, lubrication, and corrosion resistance. It has been found that a certain type of cermet is extremely effective as a material for this purpose.

Cermets are ceramics (oxides, nitrides, carbides,
It is a mixed sintered body of metal and silicide, and is generally used for tools due to its high hardness and wear resistance. However, it has various characteristics depending on the combination of ceramic and metal. From various basic experiments and considerations on metals and ceramics, the inventors found that the requirements for mold materials include heat resistance that can withstand high heat loads like molten steel, lubricity that prevents sticking of slabs and facilitates drawing, and molten copper. We have reached the conclusion that there are cermets that have a combination of metal-ceramic combinations that have a combination of corrosion resistance that minimizes corrosion and dissolution. One such cermet is molybdenum-zirconia (hereinafter referred to as MZ).
) and those with some additives added to these. Although these have been used as eel retaining tubes for thermocouples for warming the molten steel side, they have never been considered as mold materials.

Nozzles made of such heat-resistant, lubricating, and corrosion-resistant cermet
If the mold is placed horizontally and the drawing is performed intermittently, molten steel or other metals can be obtained as slabs with very slight drawing warpage.

Next, the present invention will be described in detail with reference to an embodiment of the apparatus shown in FIG. 3.

The molten metal 14 injected into the tundish 5 from the immersion nozzle 3 via the ladle 1 flow rate adjustment device (sliding nozzle) 2 is installed at the bottom of the tundish 5 and passes through the conduit 7 manufactured by Kyutai Daimono Co., Ltd. made by MZ. It flows into the nozzle mold tube 8. The outer periphery of the mold part is cooled by a copper water-cooling jacket 9, and solidification begins inside the nozzle slightly upstream of this part.

It is intermittently pulled out by pinch rolls 12 from solidified shell 15, and after leaving the mold 8, it is supported by a roll group 10 and cooled by a water souffle group 11 to completely solidify, and then cut into a predetermined length by a cutter 13.

The above horizontal CC equipment is AJ! -81 killed steel was cast. The MZ pipe has an inner diameter of 1SO, a wall thickness of 5, and a length of 500. Casting conditions are injection temperature 1550℃, drawing speed 2@/m
ln, the withdrawal-stop time is 2 seconds-2 seconds. Casting proceeded smoothly, and intermittent pull-out marks were observed in the obtained slab, but the depth was 0.5- or less and was slight. The mold was cast for about 30 minutes with almost no melting damage, and it was estimated that a much longer casting time would be possible.

As described above, according to the present invention, the conventional horizontal CC casting upper space 1 [
It is possible to prevent cold shutoff, damage and mold erosion.
Horizontal CC of molten metal, especially steel is possible], Horizontal CCO
It is possible to achieve the characteristics of equipment simplification and no straightening of cast slabs. Furthermore, it is easier to produce bloom and slab-shaped slabs by combining plate-shaped and torsion castings.The present invention is applicable not only to horizontal CC, but also to vertical casting 11, which is currently in practical use. can do. Vertical CC12J
If a caster is used in the IW part, it can be connected to a tundish to achieve subsurface solidification of the molten metal. By using the apparatus of the present invention, it is possible to remove inclusions by floating in the mold part, and to reduce oscillation and marks in the mold part.

In addition, in horizontal CC, the slab is pulled out intermittently, and in vertical CC, the slab is continuously pulled out under the mold oscillation, but these movements are the same in terms of the relative relationship between the slab and the mold. For both vertical and horizontal CCs, either stationary mold-intermittent drawing or oscillation mold-continuous drawing may be adopted.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the intermittent pull-out root, and Figure 2 is the figure 1 ■~
Fig. 2 (1) schematically shows the solidification state at the time of point (1) and (b) shows surface defects and cold cracking in the graphite molding method. FIG. 3 is a diagram showing the progress of shaft formation along with the progress of solidification, and FIG. 3 shows the i! 32IjlI diagram. 1: Ladle 2: Sliding nozzle 3: Immersion nozzle 4: Nozzle 5: Drain, 6: Oscillation device 7: Refractory conduit 8: Met pipe 9: Water-cooled soybean,)
10: o-A/Group 11: Water soufflé group 12: Pinch roll 13: Cutter 14. Molten metal 15: Solidified shell (slab) Fig. 1 ff11'r Fig. 2 drawing stroke 44
Table Stroke Figure 3 Procedural Amendment L ・Display of 11 in IF 1981 Patent Application No. 281F'50 fi Location f1
4+Qi)]! 3:! City T fee + 111 < Jinding I'll
Z Ding r16 m No. 3 Name (Name + (665)
New 11 pairs! 3:'Q J Shushitaisha 4, Agent 8 Supplementary j1 Contents Supplementary as attached.
We will amend the following matters in the original specification of the application. Add the following sentence to lul+ in the 2nd and 3rd lines of the 1st and 7th negative lines.

Claims (1)

[Claims] Continuous casting is carried out in which molten steel flows into the cocoon layer through a conduit connected to the casting 11, and the mold and conduit are heat-resistant and heat-resistant.
A continuous casting device characterized by being made of cermet that has lubrication and corrosion resistance.